The goal of the proposed research is to understand the biochemical mechanism by which neurotransmitters are released when a nerve impulse reaches an axon terminal and to determine how various polypeptide neurotoxins and low molecular weight metabolic inhibitors and other drugs alter this process. We will attempt to identify the biochemical reactions that are involved in transmitter storage and release. The studies will be performed on the following model systems: cultured PC12 cells, a clonal line from a rat pheochromocytoma and subcellular fractions from rabbit tissues.